Safety closure

ABSTRACT

A dual thread neck and cap safety closure for a container to prevent opening of the container by children yet facilitate opening the container by adults. The neck has at least two spaced apart threads, one clockwise and one counterclockwise. The cap has a corresponding clockwise thread and a corresponding counterclockwise thread.

United States Patent 91 Grulich [111 3,734,332 1 May 22,1973

1541 SAFETY CLOSURE [76 Inventor: Norman H. Grulich, 800 Longview Road,Knoxville, Tenn.

[22] Filed: Dec. 1, 1971 21 Appl. No.: 203,785

Primary Examiner-George Hall 'Attomey Lloyd McAulay [57] ABSTRACT [52]US. Cl. ..2l5/9, 215/43, 215/44 A dual thread neck and cap safetyclosure for a com [5 lilt- CI. tamer to prevent p g of the containerchildren [58] Field of Search 2154264339, 2214: yet facilitate openingthe container by adultsniThe neck has at least two spaced apart threads,one clockwise and one counterclockwise. The cap has a [56] ReferencesC'ted corresponding clockwise thread and a corresponding UNITED STATESPATENTS counterclockwise thread.

2,960,247 11/1960 Christie ..215/9 6 Claims, 4 Drawing Figures 18 l I I"'8 l f t l l I I2. l4

Patented May 22, 1973 SAFETY CLOSURE BACKGROUND OF THE INVENTION Thisinvention relates in general to safety closures and more particularly toa closure which is adapted to be used on medicine bottles and othercontainers where it is desired to keep children, particularly childrenunder 6 or 7 years of age, from opening the container while making itrelatively convenient for adults to open the container.

There has long been a need for container closures that can be readilyopened and closed repeatedly by an adult but cannot be opened by smallchildren. It is not merely containers for medicine, but also containersfor such other household items as bleach, cleaning fluids and pestpoison which require such closures.

Many safety closures have been proposed and some have been used. Onegroup of such closures relies on friction to make it impossible orunlikely for a child to have the strength necessary to open the closure.How-,

ever, such closures had the disadvantage that elderly people and othersick adults frequently do not have the strength necessary to open andproperly close the containers involved. A person with arthritic fingershas great difficulty opening some of the aspirin bottle safety closuresthat have been employed. Furthermore, some of the known and proposedclosures place such force on the friction creating elements that thereis a real risk that the closure will break after a number of uses.

Accordingly, it is an important purpose of this invention to achievethis child-proof safety closure in a design which will permit elderlypersons and ill adults, whose strength may be no greater than that ofthe children to which the design is directed, to open thebottle readilyand to close it again.

It is another purpose of this invention to devise a safety closure thatwill not break after repeated use.

Another group of known safety closures are so complex that many adultshave difiiculty opening them. Such complex closures require expensiveand complex special machinery for forming the closure and/or for cappingthe container in production. Such complexities tend to prevent the useof these safety closures in the wide range of applications for which itis desired to have such a closure.

Accordingly, it is another purpose of this invention to provide arelatively simple and relatively inexpensive childproof safety closure.

More particularly, it is a purpose of this invention to provide a safetyclosure which is relatively inexpensive to manufacture and which isrelatively inexpensive to incorporate into an automatic containerfilling and capping assembly line.

Because of the nature of the contents that are contained in thosecontainers where safety closures are required, it is an importantpurpose of this invention to provide a safety closure that meets theabove criteria but which also can be made as airtight as required.

To facilitate widespread adoption of a child-proof safety cap, it is afurther object of this invention to provide a design which will avoidobsoleting presently installed filling and capping machinery.

It is yet another object of this invention to provide a chile-proofsafety closure that can be used on squeeze tubes without requiring thatthe squeeze tube be held so tightly when being uncapped as to deform thetube.

BRIEF DESCRIPTION OF THE INVENTION In brief, this invention involves theuse of a first clockwise screw thread around the lower portion of theneck of a container and a second counterclockwise screw thread aroundthe upper portion of the neck of the container. These two threads arespaced apart on the neck by an amount and for a reason that relates tothe cap structure. The cap which fits over the neck of the container hasa clockwise thread close to the cap rim that mates with the lowerclockwise thread on the neck. Further into the cap is a counterclockwisethread that mates with the upper thread on the neck.

The peak diameter of the upper counterclockwise thread on the neck issufficiently less than the diameter across the peaks of the lowerclockwise thread on the cap so that the latter can readily pass over theformer without engagement when the cap is placed over the neck.

The two cap threads are substantially axially adjacent to one another.The spacing between the two neck threads is at least equal to the totalaxial length of both cap threads taken as a unit.

In operation, the cap is fitted onto the neck by placing the cap overthe neck until the upper counterclockwise thread in the cap contacts theupper counterclockwise thread on the neck. By turning the capcounterclockwise, these threads engage and the counterclockwise movementis continued until the upper thread on the cap passes entirely throughthe upper thread on the neck. At that point, both threads in the cap arein the space areas between the two threads on the neck. The cap is thencontinued to be brought down over the neck by changing the direction ofrotation of the cap from counterclockwise to clockwise, so that thelower thread on the cap engages the lower thread on the neck. To removethe cap requires reverse movement, first rotating counterclockwise tounscrew the lower neck and cap threads from one another, and thenclockwise to unscrew the upper neck and cap threads from one another.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of theneck of a container incorporating this invention.

FIG. 2 is a cross-section through a cap designed to fit over and closeoff the neck shown in FIG. 1.

FIG. 3 is a perspective view of the neck of an alternate embodiment ofthis invention.

FIG. 4 is a cross-section through a cap designed to fit over and closeoff the neck shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 illustrate thesame embodiment. As shown therein, a container 10 (not completely shown)has a neck portion 12. On the outside circumference of the neck 12 thereis a lower screw thread 14 having a first rotational direction and anupper screw thread 16 having the opposite rotational direction. Betweenthe two threads 14 and 16 there is an appreciable blank space 18. Justas an example, in one embodiment the lower thread 14 has three turns ina clockwise direction and the upper thread 16 has three turns in acounterclockwise direction.

In order to permit proper cooperation with the cap shown in FIG. 2, theupper thread 16 peak diameter D is less than the root diameter of thelower thread 14. The axial length of the space 18 depends upon the axiallength of the threads in the .cap but in most embodiments, this lengthwill be approximately at least equal to the sum of the axial length ofthe neck lower thread 14 and neck upper thread 16.

On the inside circumferential surface of the cap 22, there 'is a lowerscrew thread 24 and an upper screw thread 26. The cap lower thread 24has a rotational direction such that it can be mated with the neck lowerthread 14. The cap upper thread 26 has a rotational direction such thatit can be mated with the neck upper thread 16. Thus, the rotationaldirections of the cap lower thread 24 and cap upper thread 26 areopposite to one another. The cap lower thread 24 and upper thread 26need be no more spaced from one another axially than is convenient andnecessary in order to fabricate two threads having opposite rotationaldirections.

In order for this dual screw thread safety cap to operate, it isessential that the cap lower screw thread 24 pass axially over the neckupper screw thread 16. Ac-

. cordingly, the peak diameter D of the lower screw thread 24 in the cap22 must be greater than the peak diameter D of the cap upper screwthread 16.

A further dimensional relationship, in order to permit operation of thisinvention, is that the axial length of the two cap screw threads 24 and26 taken as a unit must be equal to or less than the axial distance N ofthe space 18 on the neck 12 between the two neck screw threads 14 and16. This dimensional relationship is necessary so that after the capupper thread 26 has completely threaded through the neck upper thread16, both cap screw threads 24 and 26 will fit within the space 18. Thisfit in turn is required so that the cap lower thread 24 can then bethreaded onto the neck lower thread 14 in order to effect closure.

The axial dimensions of the neck 12 and cap 22 may be such that the neck12 upper rim 28 abuts against the back inner surface 30 of the cap 22,when the cap lower thread 24 is threaded onto the neck lower screwthread 14, so as to effect a substantially air-tight type of seal.

OPERATION In operation, the cap 22 is mated to the neck 12 by firstrotating the cap 22 on the neck 12 in one rotational direction (forexample, counterclockwise) and then rotating the cap 22 on the neck 12in an opposite rotational direction (clockwise in the examplehypothesized).

More specifically, the cap 22 is brought down over the neck 12 and thecap lower screw thread 24 passes over the neck upper screw thread 16until the cap upper screw thread 26 contacts the neck upper screw thread16. Next, the rotation counterclockwise (as one example) causes the capupper screw thread 26 to thread through the neck upper screw thread 16until both cap screw threads 24 and 26 are positioned within the blankneck space 18. Obviously the neck space 18 must have a diameter lessthan the peak diameter of either cap screw thread 24, 26. Next, the capis rotated clockwise to cause the cap lower screw thread 24 to threadonto the neck lower screw thread 14.

In order to remove the cap, the user must know to first rotate the capcounterclockwise (thereby unscrewing the thread 24 from the thread 14)and then, pulling the cap axially up, rotate the cap clockwise (therebythreading the screw thread 26 through the screw thread 16).

ALTERNATE EMBODIMENT FIGS. 3 and 4 show an alternate embodiment which issimilar to FIGS. '1 and 2 except that the manner of causing the caplower screw thread to pass over the neck upper screw thread isdifferentQAccordingly', in the embodiment shown in FIGS. 3and 4, thesame reference numerals are used as are used in FIGS. 1 and 2, except asto the'variant features and, as to those variant features, a parallelreference numeral system is employed.

In this FIG. 3 embodiment, the diameter of the neck lower screw thread14 and the neck upper screw thread 116 is essentially the same.Accordingly, the diameter of the cap screw threads 124 and 26 are thesame. In order for the cap lower screw thread 124 to pass over the neckupper screw thread 116, these two screw threads 116 and 124 areconstructed in an intermittent or broken fashion as shown. These threads116 and 124 each have alternate, preferably equal, axial zones 116a,

124a in which the thread is obliterated. The remaining portion of thethreads 116 and 124 can then pass axially through one another much inthe manner that axial splines would pass through one another. Althoughthis is not a preferred embodiment, it is one way in which the steppeddiameter of the neck and cap can be avoided.

Although the terms upper and lower are used in the specification andclaims to refer to the two neck threads relative to each other and tothe two cap threads relative to each other, it should be understood thatthis terminology is not limiting. Normally, of course, the neck threadclosest to the rim 28 will be an upper neck thread because the container10 will normally be held with its neck up. Obviously, however, the

container might be in any orientation and it is to be understood hereinthat this change in orientation does not affect the scope of thisinvention. The terms upper and lower are used for convenience ofvisualization and it is to be understood that the upper thread of theneck is the one nearest to the rim of the neck and the lower thread ofthe cap is the one nearest to the rim of the cap.

I claim:

1. A safety closure for a container having a neck and a mating capcomprising:

a first screw thread on the outer surface of the neck, said first threadhaving a first rotational direction,

a second screw thread on the outer surface of the neck positioned aboveand spaced from said first thread, said first and second screw threadshaving opposite rotational directions,

a third screw thread on the inner surface of the cap,

said third screw thread having a rotational direction permitting saidthird screw thread to be threaded onto said first screw thread,

a fourth screw thread on the inner surface of said cap and positionedabove said third screw thread, said fourth screw thread having arotational direction permitting it to be threaded onto said second screwthread,

said first and second screw threads on the neck being axially spacedapart by a distance at least equal to the axial length of thecombination of said third and fourth screw threads on said cap, and

means to permit said third thread to axially pass said second thread.

2. The closure of claim 1 wherein:

the peak diameter of said second thread is less than the peak diameterof said third thread so that said third thread can pass axially oversaid second thread.

3. A safety closure for a container having a neck and mating cap toinhibit opening by children comprising:

a first screw thread on the outer surface of the neck,

a second screw thread on the outer surface of the neck,

the rotational directions of said first and second screw threads beingopposite to one another,

a third screw thread on the inner surface of said cap,

a fourth screw thread on the inner surface of said cap,

said third and fourth screw threads having rotational directionsopposite to one another,

said first screw thread being lower on the neck than said second screwthread and said third screw thread being lower on the cap than saidfourth screw thread,

said third screw thread being adapted to engage said first screw threadand said fourth screw thread being adapted to thread onto said secondscrew thread,

said first and second threads being axially spaced apart on said neck bya distance at least equal to the axial length of said third and fourththreads as a unit, and

means to permit said third thread to axially pass said second thread.

4. The closure of claim 3, wherein:

the peak diameter of said second thread is less then the peak diameterof said third thread so that said third thread can pass axially oversaid second thread.

5. A container having a neck adapted to be closed by a cap to provide asafety closure to inhibit opening by children comprising:

a lower screw thread on the outer surface of said neck having a firstrotational direction, and

an upper screw thread on the outer surface of said neck having a secondrotational direction,

said first and said second rotational directions being opposite to oneanother,

said upper and lower screw threads on said neck being axially spacedfrom one another by a distance sufficient to accommodate mating capscrew threads,

the peak diameter of said upper screw thread being less than the rootdiameter of said lower screw thread.

6. A safety closure cap for a container having a neck to provide incombination with the container a closure that inhibits opening bychildren comprising:

an upper screw thread on the inner surface of said cap, and

a lower screw thread on the inner surface of said cap axially positionedcloser to the rim of the cap than said upper screw thread,

the rotational directions of said upper and lower screw threads beingopposite to one another,

the peak diameter of said lower screw thread being greater than the rootdiameter of said upper screw thread.

1. A safety closure for a container having a neck and a mating capcomprising: a first screw thread on the outer surface of the neck, saidfirst thread having a first rotational direction, a second screw threadon the outer surface of the neck positioned above and spaced from saidfirst thread, said first and second screw threads having oppositerotational directions, a third screw thread on the inner surface of thecap, said third screw thread having a rotational direction permittingsaid third screw thread to be threaded onto said first screw thread, afourth screw thread on the inner surface of said cap and positionedabove said third screw thread, said fourth screw thread having arotational direction permitting it to be threaded onto said second screwthread, said first and second screw threads on the neck being axiallyspaced apart by a distance at least equal to the axial length of thecombination of said third and fourth screw threads on said cap, andmeans to permit said third thread to axially pass said second thread. 2.The closure of claim 1 wherein: the peak diameter of said second threadis less than the peak diameter of said third thread so that said thirdthread can pass axially over said second thread.
 3. A safety closure fora container having a neck and mating cap to inhibit opening by childrencomprising: a first screw thread on the outer surface of the neck, asecond screw thread on the outer surface of the neck, the rotationaldirections of said first and second screw threads being opposite to oneanother, a third screw thread on the inner surface of said cap, a fourthscrew thread on the inner surface of said cap, said third and fourthscrew threads having rotational directions opposite to one another, saidfirst screw thread being lower on the neck than said second screw threadand said third screw thread being lower on the cap than said fourthscrew thread, said third screw thread being adapted to engage said firstscrew thread and said fourth screw thread being adapted to thread ontosaid second screw thread, said first and second threads being axiallyspaced apart on said neck by a distance at least equal to the axiallength of said third and fourth threads as a unit, and means to permitsaid third thread to axially pass said second thread.
 4. The closure ofclaim 3, wherein: the peak diameter of said second thread is less thenthe peak diameter of said third thread so that said third thread canpass axially over said second thread.
 5. A container having a neckadapted to be closed by a cap to provide a safety closure to inhibitopening by children comprising: a lower screw thread on the outersurface of said neck having a first rotational direction, and an upperscrew thread on the outer surface of said neck having a secondrotational direction, said first and said second rotational directionsbeing opposite to one another, said upper and lower screw threads onsaid neck being axially spaced from one another by a distance sufficientto accommodate mating cap screw threads, tHe peak diameter of said upperscrew thread being less than the root diameter of said lower screwthread.
 6. A safety closure cap for a container having a neck to providein combination with the container a closure that inhibits opening bychildren comprising: an upper screw thread on the inner surface of saidcap, and a lower screw thread on the inner surface of said cap axiallypositioned closer to the rim of the cap than said upper screw thread,the rotational directions of said upper and lower screw threads beingopposite to one another, the peak diameter of said lower screw threadbeing greater than the root diameter of said upper screw thread.